Method of regenerating mercury catalysts.



NATHAN Gm'iNs'rEIN, or FRANKFORT-ON-THEFMAIN, GERMANY, ASSIGNOB. To THEFIB-1L OF CHEMISCHE FABRIK GRIESHEIM-ELEKTRON, MAIN, GERMANY,A"COBPOR-ATION F GERMANY.

OF FRANKFORT-ON-THE- METHOD OF REGENERATING MERCURY CATALYSTS.

Specificatiouof Letters Patent.

Patented May 30, 1916.

- No Drawing. Original application filed August '4, 1915. Serial No.43,667. Divided and this application .filedjanuary 4, 1916. Serial No.70,321.

duced and becomes ineffective.

To all whom it may concern:

Be it known that I, NATHAN Gnii vs'rnriv, a "subject of the Emperor ofRuss1a, and

resident of Frankfort-on-the-Main, Germany, have invented certain new.and use ful Improvements in the Method .of Regenerating MercuryCatalysts, of which the.

sides the liquid mercury more or less of a mercury sludge is formedwhich can be regenerated only with great difliculty. I have nowascertained that it is easy to regenerate such exhausted mercurycatalysts by reducing the mercury sludge first of all into the metallicstate and then converting the metal into compounds suitable for use ascatalysts- In an earlier application, Serial Number 43,667, filed August4, 1915, of which the present case is a division, I have described andclaimed one method of regenerating such mercury catalysts.

In the practice of my invention as hereinafter described I regeneratethe exhauted mercury catalysts by subjecting the mercury sludge inalkaline solution to the action of the electric current. By thistreatment the sludge is transformed without any losses into liquidmercury which-may then be converted, either by electrolysis or by anyother means, into the catalytic active compounds. Example I: 200 partsof a mercury sludge obtained by producing aldehyde from acety lene insulfuric acid solution are freed from the impurities by washing; 4:00partsof a 10 per cent. solution of caustic soda are then added and themixture is subjected under continuous stirring to, electrolysis at 40 todegr. C. and to 3 to 6 volt. Iron electrodes are preferably employed.While the solution-is foaming the mercury sludge is completely convertedinto liquid metallic mercury. It is merely necessary to pro vide for theaddition of fresh sludge, which may be fed in either intermittently orcontinuously. The pure liquid mercury obtained can be transformed,either by electrolysis or in any other way, into mercurous or mercuriccompounds which may then be used again as'catalysts. The regeneration ofmercury sludge formed. in phosphoric acid or sulfo acid solution takesplace in the same way. Part of the impurities contained in the sludge isburned by the current while the remainder is suspended in the lye whichmay be separated from it from time to time by decantationand may be usedagain. At the cathode some mercury amalgam separates out.

The degree of concentrating the caustic soda and potash solution may bevaried, and so may the temperature.

Further experiments have shown that the exhausted mercury catalysts'canbe regenerated also by treating great quantities of such catalysts withacetylene in acid solution and at higher temperature. ascertained theinteresting'f'act that mercury catalysts which have been almostexhausted in the normal process still show a satisfactory catalyticaction provided that greater quantities are used, a great part of themercury sludge being in this case reduced to liquid metal. Under certainconditions it is even possible to convert the whole of the sludge intoliquid metal.

In regenerating the catalyst in an acid solution it is preferable not touse the catalysts'in the normal process up to complete exhaustion, butto remove them as soon as their catalytic effect shows a visible diminu-I have tion, in order to subject greater quantities thereof to theultimate regenerating treatment. 4

In practising the invention on a commercial scale I prefer combining thetwo modifications of my regenerating method in such a way that thecatalysts exhausted in the normal process is first treated in greaterquantities and in acid solution with acetylene, thus transforming-thegreater part of the sludge into liquid metal, and the residual sludge isthen regenerated in alkaline solution by the action of. the electriccurrent.

Example II: 300 tained as above are treated at 60 to 90 degr. C. withacetylene in 500 parts of diluted acid such as a 3 to 5 per cent.sulfuric acid.

The process is preferably carried out in the following manner: An excessof acetylene 1s lntroduccd into the liquld which is stirred I thereby,the aldehyde in excess is freed from aldehydeby Washing and isintroduced into the liquid afresh. acetylene is carried on as long as aformation of aldehyde can beascertained. By this treatment aconsiderable part of the sludge is converted into liquidrmetallicmercury.

Another considerable part of the sludge may be converted into liquidmercury by washing and drying. The regeneration of the remainder ispreferably carried out by electrolysis in an alkaline solution as de- Iscribed in Example I.

. I claim: v 1. The method of regenerating mercury catalysts Which aretransformed into sludge parts of sludge ob- The treatment with catalystswhich consists in first subjecting great quantities of the partiallyexhausted catalysts to treatment With acetylene in an acid solution to.convert the greater part of them into metallic mercury, and transformingthe remainder into metallic mercury by electrolysis in an alkalinesolution. a

In testimony whereof I have signed my name to this specification in thepresence of two subscribing Witnesses.

NATHAN GRUNS EIN.

Witnesses CARL GRUND, ERNEST L. Ivns.

